1. Field of the Invention
This invention relates to a three dimensional display wherein the three dimensional image is generated from a diffractive element and, more specifically, a holographic scanner.
2. Brief Description of the Prior Art
Three dimensional display are known in the prior art. Such a display is created using a rotating display surface which receives light scanned or modulated in a two axis (x-y) area as set forth in U.S. Pat. No. 5,042,909, the contents of which are incorporated herein by reference. Such systems are known as multiplanar volume display systems. To implement such systems, the prior art utilized acousto/optic deflectors to achieve the x-y modulation or scanning. The fact that the prior art acousto/optic scanners have limited speed and are high in cost implies that a new approach is necessary wherein speed and/or cost can be reduced.
Rotational scanners, such as polygonal mirrors, hologons, etc., have been used for many years to generate x-y scan patterns for bar code readers, laser printers and many other optical devices. It has also been known in the prior art that a rotational scanner can produce an x-y scan pattern wherein a laser beam is transmissively or reflectively dispatched. Volume display images require specific addressing in the x-y plane at specific times in the cycle of the rotating display disk. These specific times are known as a time slice. For every time slice, a specific x-y plane must be scanned to created voxels of the volume (three dimensional) image.